Method of assembly of composite core sandwich edge joint

ABSTRACT

A method for assembling a composite wall assembly edge joint including laying up a first composite face sheet, laying up a first composite buildup pad having a first tapered section onto the first composite face sheet and positioning a composite flute core member, including a tapered first portion with a first inclined surface and a second inclined surface. First inclined surface is positioned onto the first tapered section of the first composite buildup pad and a second portion of the composite flute core member extends from the tapered first portion along first composite face sheet. The method also includes laying up a second composite buildup pad having a second tapered section with the second composite buildup pad spaced apart from the first composite buildup pad and having at least a portion of the second tapered section overlying the second inclined surface of the tapered first portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent application Ser. No. 15/432,024, filed Feb. 14, 2017. The entirety of each of the foregoing provisional applications is incorporated by reference herein.

FIELD

This disclosure generally relates to a method to assemble an edge joint for composite materials and more particularly a method to assemble an edge joint for composite sandwich shell edges.

BACKGROUND

Composite structures are being developed to replace aluminum components for use with space launch vehicles. Replacement of aluminum components with lighter, lower cost, and less thermally conductive composite components will enable larger payloads, reduced operating costs and longer missions due to propellant boil-off reduction.

In the construction of the composite structures, composite fluted core sandwich shell wall assemblies were employed. These wall assemblies were used, for example, in the construction of an external structural wall assembly of a rocket or in the construction of a cryogenic tank assembly. Sections of the wall assemblies were joined together with joint edge structures so as to connect adjoining sections of the structure being assembled. As higher line load demands are encountered and needed than originally used in smaller rockets or structures positioned higher in a stack, for example, an improved edge joint construction is needed for constructing the structural assembly with composite fluted core sandwich shell wall sections.

The lighter load shell edge joints originally developed required relatively large openings between intermittently spaced shell edge reinforcements to allow extraction of tooling. As a result of the relatively large openings, that construction did not permit more closely spaced fasteners that would be needed for a joint that needed to carry a higher load capacity. The lighter load shell edge joint construction also forced load into the face sheets of the structure at the ends of the flutes which necessitated positioning a local doubler for carrying higher loads for which the original joint was not designed.

An improved method to assemble a composite wall assembly edge joint that will provide improved load carrying capabilities such that more load can be carried and distributed permitting additional and more closely spaced fasteners. This improved shell edge joint performance for increased load capacity needs to be accomplished with minimizing the increase in vehicle weight.

SUMMARY

An example method includes a method for assembling a composite wall assembly edge joint which includes steps of laying up a first composite face sheet, laying up a first composite buildup pad having a first tapered section onto the first composite face sheet and positioning a composite flute core member, which includes a tapered first portion comprising a first inclined surface and a second inclined surface. The first inclined surface of the composite flute core member is positioned onto the first tapered section of the first composite buildup pad and a second portion of the composite flute core member extends from the tapered first portion along first composite face sheet. The method further includes the step of laying up a second composite buildup pad having a second tapered section wherein the second composite buildup pad is positioned spaced apart from the first composite buildup pad having at least a portion of the second tapered section of the second composite buildup pad overlying the second inclined surface of the tapered first portion of the composite flute core member.

Another example method includes a method for assembling a composite wall assembly edge joint, comprising steps of laying up a composite first face sheet, laying up a composite first buildup pad having a first tapered section onto the composite first face sheet and positioning a cured composite flute core member which includes a tapered first portion including a first inclined surface and a second inclined surface. The first inclined surface of the cured composite flute core member is positioned onto the first tapered section of the for composite buildup pad with an adhesive film positioned between the first inclined surface and first tapered section. A second portion of the composite flute core member extends from the tapered first portion along first composite face sheet wherein an adhesive film is positioned between the second portion of the composite flute core member and the first composite face sheet. The method further includes the step of laying up a second composite buildup pad having a second tapered section wherein the second composite buildup pad is positioned spaced apart from the first composite buildup pad having at least a portion of the second tapered section overlying the second inclined surface of the tapered first portion of the composite flute core member with an adhesive layer positioned between the second tapered section and the second inclined surface of the tapered first portion of the composite flute core member.

The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings.

BRIEF SUMMARY OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a rocket showing an edge joint location on wall of rocket;

FIG. 2 is a partial cut away perspective view of a cross section of the rocket shown in FIG. 1 with a cryogenic propellant tank on board;

FIG. 3 is a an enlarged partial cut away view of the joint edge of a composite wall assembly of that which is encircled and designated as 3 in FIG. 2;

FIG. 4 is cross section view taken along line 4-4 in FIG. 3;

FIG. 5 is a perspective view of a composite flute core member of the composite wall assembly shown in FIG. 3;

FIG. 6 is an enlarged partially cut away view of tapered end of the composite flute core member in FIG. 5;

FIG. 7 is a cross section view of the joint edge of the composite wall assembly as seen along line 7-7 in FIG. 3;

FIG. 8 is a perspective view of cross section as taken along line 4-4 of FIG. 3;

FIG. 8A is an enlarged view of that which is encircled as 8A in FIG. 8;

FIG. 9 is a flow chart for a method for assembling a composite wall assembly edge joint;

FIG. 10 is a flow chart for a second example of a method for assembling a composite wall assembly edge joint;

FIG. 11 is a cross section view of the joint edge of the composite wall assembly as seen along line 7-7 in FIG. 3 wherein this joint edge is assembled in accordance with the second example of the method for assembling a composite wall assembly edge joint as set forth in FIG. 10;

FIG. 12 is the cross section as shown in FIG. 4 wherein the composite flute core member is supported with a collapsible support during layup of an edge joint assembly for the second example of the method for assembling the composite wall assembly edge joint;

FIG. 13 is a cross section view showing the providing of support between spaced apart first and second composite buildup pads during assembly of edge joint;

FIG. 14 is a flow chart for a third example of a method for assembling a composite wall assembly edge joint; and

FIG. 15 is an enlarged view of that which is encircled as 8A in FIG. 8 showing an edge joint assembled in accordance with the third example of the method for assembling a composite wall assembly edge joint as set forth in FIG. 14.

DESCRIPTION

As mentioned earlier, composite structures are being developed to replace aluminum components or structures for use with a space launch vehicle or rocket 10, such as shown in FIGS. 1 and 2. Replacement of aluminum components with lighter, lower cost, and less thermally conductive composite components will enable larger payloads, reduced operating costs and longer missions due to propellant boil-off reduction.

In the construction of the composite components or structures, an example of such components or structures include using composite fluted core sandwich shell wall assemblies. These wall assemblies are used, for example, in the construction of different portions of rocket or launch vehicle 10 such as for an external structural wall assembly 12 of rocket 10, or in another example for a cryogenic propellant tank with a skirt assembly 14, as seen in FIGS. 1 and 2, respectively. Other components of various versions of rocket 10 can also be constructed with composite structures such as, an inter stage section for a multiple stage rocket as well as for other portions of a rocket. As mentioned above, an example of assembling a composite sandwich shell wall assembly 12 with an improved joint edge 16 will be discussed herein. Improved joint edge 16 joins together, in this example, first section 18 to second section 20 of wall assembly 12 and will provide improved performance for higher line load demands with minimizing weight increase in vehicle or rocket 10.

In referring to FIG. 3, edge joint 16 is shown connecting first section 18 to second section 20 of wall assembly 12. Composite fluted core sandwich shell wall assembly 12 includes first or inboard composite face sheet 22 and spaced apart second or outboard composite face sheet 24. Positioned within the spaced apart first and second composite face sheets 22 and 24 are a plurality of flute composite core members 26. An example of flute composite core member 26 is shown in FIGS. 5 and 6. In this example of wall assembly 12, flute composite core members 26 are trapezoidal in shape, as seen in FIG. 4 however the shape can be selected from one of a number of shapes. In this example, trapezoidal shaped flute composite core members 26 are positioned between first and second composite face sheets 22, 24 in succession forming core assembly 28, as seen in FIG. 4. Flute composite core members 26 can be further reinforced with employing a noodle 30 structure positioned in a cavity 32 that forms between adjacent radiuses 31 and 33 of flute composite core members 26 and first composite face sheet 22, as well as, between adjacent radiuses 35 and 37 of flute composite core members 26 and second composite face sheet 24. Wall assembly 12 with core assembly 28 provides a strong and lightweight construction.

In referring to FIGS. 5-8A, composite fluted core sandwich wall assembly 12 with edge joint 16 is shown which accommodates higher line load demands exerted through edge joint 16, whether exerted in compression or in tension. In referring to FIG. 7, first composite buildup pad 34 having first tapered section 36 is secured to and extends along first or inboard composite face sheet 22. Second composite buildup pad 38 having a second tapered section 40 is secured to and extends along second or outboard composite face sheet 24. First and second composite buildup pads 34 and 38 are positioned between spaced apart first and second composite face sheets 22 and 24. Composite flute core member 26 includes tapered first portion 42 and is positioned between and secured to first tapered section 36 and to second tapered section 40. Second portion 44, as seen in FIG. 5, of composite flute core member 26 is positioned between, extends along and is secured to first and second composite face sheets 22 and 24. Second portion 44 of composite flute core member 26 extends in direction 46 away from first portion 42. This construction of tapered first portion 42 of flute composite core member 26 being secured to first and second tapered sections 36 and 40 of first and second composite buildup pads 34 and 38, respectively, provides enhanced load line capabilities for joint edge 16.

As seen in FIGS. 7, 8 and 8A, first composite buildup pad 34 extends in a direction 48 away from first end 50 of first or inboard composite sheet face 22. First tapered section 36 of first composite buildup pad 34 has first inclined surface 52 with a thickness T of first tapered section 36 reducing in dimension as first composite buildup pad 34 extends in direction 48 away from first end 50. Second composite buildup pad 38 extends in direction 54 away from second end 56 of second or outboard composite sheet face 24. Second tapered section 40 of second composite buildup pad 38 has second inclined surface 64 with thickness T′ of second tapered section 40 reducing in dimension as second composite buildup pad 38 extends in direction 54 away from second end 56.

First portion 42 of flute core member 26 has first inclined surface 58 relative to first composite face sheet 22. Inclined surface 58 extends along first inclined surface 52 of first composite build up pad 34 such that first inclined surface 58 of first portion 42 of composite flute core member 26 is positioned further from first composite face sheet 22 as first portion 42 of composite flute core member 26 extends in direction 60 toward first end 50 of first composite face sheet 22. First portion 42 of composite flute core member 26 has second inclined surface 62 relative to second or outboard face sheet 24 which extends along second inclined surface 64 of the second build up pad 38 such that second inclined surface 62 of first portion 42 of composite flute core member 26 is positioned further from second or outboard face sheet 24 as first portion 42 extends in direction 66 toward second end 56 of second composite face sheet 24.

As seen in FIGS. 5 and 6, first portion 42 of composite flute core member 26 includes first wall member 68 with first inclined surface 58 of first portion 42 of composite flute core member 26 positioned on first wall member 68. First portion 42 of composite flute core member 26 includes second wall member 70 with second inclined surface 62 of first portion 42 of composite flute core member 26 is positioned on second wall member 70. First wall member 68 and second wall member 70 are spaced apart a as seen for example as distance D, as seen in FIG. 6, and converge as first wall member 68 extends in direction 60 of first end 50 of first composite face sheet 22, as seen in FIG. 7, and second wall member 70 extends in direction 66 of second end 56 of the second composite face sheet 24.

As seen in FIGS. 5-8A, first inclined surface 58 of first portion 42 of composite flute core member 26 is co-cured to first inclined surface 52 of first composite build up pad 34. Second inclined surface 62 of the first portion 42 of the composite flute core member 26 is co-bonded to the second inclined surface 64 of second composite build up pad 38. Second portion 44 of composite flute core member 26 is co-bonded to first composite face sheet 22 and to second composite face sheet 24. First composite build up pad 34 is co-bonded to first composite face sheet 22 and second composite build up pad 38 is co-cured to second composite face sheet 24.

In referring to FIGS. 7, 8 and 8A, bridge composite structure 72 is positioned between first composite buildup pad 34 and second composite buildup pad 38. Bridge composite structure 72 is secured to both first and second build up pads 34 and 38 and extends along first composite buildup pad 34 in direction 48 away from first end 50 of first composite face sheet 22 and extends along second composite buildup pad 38 in direction 54 away from second end 56 of second composite face sheet 24.

Bridge composite structure 72, in this example, is post bonded to first composite build up pad 34 and is post bonded to second composite build up pad 38. Further included is first hole 74 which extends in first direction 76 through first composite sheet face 22, first composite build up pad 34, bridge composite structure 72, second composite buildup pad 38 and second composite face sheet 24. First portion 78 of second hole 80 extends through bridge composite structure 72 in second direction 82 transverse to first direction 76 of first hole 74 such that first portion 78 of second hole 80 is in communication with first hole 74 and second portion 84 of second hole 80 extends within bridge composite structure 72 in second direction 82 spaced apart across first hole 74 and aligned with first portion 78 of second hole 80.

Further included is barrel nut 86 having hole 88, which extends through barrel nut 86, with barrel nut 86 positioned within first hole 74 of bridge composite structure 72. Barrel nut 86 has threaded surface 90 defined by inner wall surface 92 of hole 88 with hole 88 of barrel nut 86 positioned aligned with first and second portions 78 and 84 of second hole 80 of bridge composite structure 72. Bolt 94 includes threads 96 compatible to threaded surface 90 defined by the inner wall surface 92 of hole 88 of barrel nut 86. Bolt 94 is positioned within first portion 78 of second hole 80 of bridge composite structure 72. Threads 96 of bolt 94 engage threaded surface 90 defined by inner wall surface 92 of hole 88 of barrel nut 86. With bolt 94 engaged and tightened, as seen in FIG. 7, first section 18 is secured to second section 20 of wall assembly 12.

As will be appreciated in the discussion of an example of the assembly of edge joint 16, composite bridge structure 72 will be installed as a latter element in the joint edge 16 construction which includes the components of first composite or inboard sheet face 22, first composite buildup pad 34, flute composite core member 26, second composite buildup pad 38 and second composite or outboard face sheet 24. With these components assembled composite bridge structure 72 is installed along wall assembly 12. Composite bridge structure 72 can provide the fabricator as needed a substantially continuous wall which extends about wall assembly 12 in which to drill second holes 80 with intersecting corresponding first holes 74. With a substantially continuous wall established by bridge composite structure 72, the fabricator has the flexibility of selectively spacing connecting assemblies of barrel nuts 86 and bolts 94 along joint edge 16 of wall assembly 12 to accommodate load demands as needed through joint edge 16 along wall assembly 12 in connecting, for example, section 18 to section 20 of wall assembly 12. As a result, the fabricator selects the spacing and employs the spacing, as can be seen for example in FIG. 3, as required for load transference across joint edge 16. The load lines will extend along first and second buildup pads 34 and 38, along first and second tapered sections 36 and 40, engage first and second walls 68 and 70 of composite flute core member 26 and in turn extend into first and second face sheets 22 and 24 providing joint edge 16 with an enhanced performance for wall assembly 12.

In referring to FIG. 9, an example of method 100 for assembling composite fluted core sandwich shell wall assembly 12 edge joint 16 is shown. Method 100 includes step 102 of laying up first composite buildup pad 34 having a first tapered section 36 onto a cured first composite or inboard face sheet 22, with an adhesive layer 43, as seen in FIG. 8A, positioned between first composite buildup pad 34 and first composite face sheet 22. Step 102 of laying up first buildup pad 34 further includes the step of laying up of first buildup pad 34 which extends in a direction 48 away from first end 50 of first composite face sheet 22 and configuring first tapered section 36 having first inclined surface 52 with thickness T of first composite buildup pad 34 reducing in dimension as first composite buildup pad 34 extends in direction 48 away from first end 50.

Method 100 further includes step 104 of positioning composite flute core member 26, which includes tapered first portion 42, having a first inclined surface 58 and a second inclined surface 62, wherein, first inclined surface 58 of composite flute core member 26 is positioned onto first tapered section 36 of first composite buildup pad 34. Second portion 44 of composite flute core member 26, as seen in FIG. 5, extends in direction 46 away from first portion 42 along first composite or inboard face sheet 22, as seen in FIGS. 7 and 8A, with adhesive film 43 positioned between second portion 44 of flute composite core member 26 and first composite face sheet 22. Step 104 of positioning of composite flute core member 26 further includes positioning first inclined surface 58 of composite flute core 26 overlying first inclined surface 52 of first composite buildup pad 34 such that first inclined surface 58 of composite flute core member 26 increases in distance away from first composite face sheet 22 as composite flute core member 26 extends in a direction 60 toward first end 50 of first composite sheet face 22.

Method 100 further includes step 106 of heating at least first composite buildup pad 34 and composite flute core member 26, co-curing first composite buildup pad 34 and composite flute core member 26 and securing together first tapered section 36 of first composite buildup pad 34 with first inclined surface 58 of composite flute core member 26 and co-bonding second portion 44 of composite flute core member 26 to first composite or inboard face sheet 22. At the same time, first composite build up pad 34 is co-bonded to first composite face sheet 22.

Method 100 further includes step 108 of laying up second composite buildup pad 38 having a second tapered section wherein the second composite buildup pad is positioned spaced apart from first composite buildup pad 34 and with at least a portion of the second tapered section of second composite buildup pad 38 overlying an adhesive film 39, as seen in FIG. 8A, positioned overlying second inclined surface 62 of first portion 42 of composite flute core member 26. Step 108 of laying up second composite buildup pad 38 includes configuring second inclined surface 64 of second composite buildup pad 38 with second composite buildup pad 38 reducing in thickness T′ as second composite buildup pad 38 extends in direction 54 away from second end 56 of second composite face sheet 24 with second inclined surface 62 of first portion 42 of composite flute core member 26 decreases in distance from first composite face sheet 22 as second inclined surface 62 of composite flute core member 26 extends in direction 60 toward first end 50 of first composite face sheet 22.

With second composite buildup pad 38 positioned overlying second inclined surface 62 of composite flute core member 26 step 110 is employed of heating at least second composite buildup pad 38 and co-bonding second composite buildup pad 38 to second inclined surface 62 of first portion 42 of composite flute core member 26.

Step 108 of laying up second composite buildup pad 38 further includes the step of laying up a second composite face sheet 24 onto second composite build-up pad 38 and onto second portion 44 of composite flute core member 26 with positioning adhesive film 39 between second portion 44 of composite flute core member 26 and second composite face sheet 24, as seen in FIG. 8A. Step 110 of heating at least second composite buildup pad 38 further includes co-curing second composite buildup pad 38 and second composite face sheet 24 together and co-bonding second portion 44 of composite flute core member 26 to second composite face sheet 24.

Method 100 further includes a step of laying up composite bridge structure 72 and post bonding composite bridge structure 72 to first and second composite buildup pads 36 and 38 respectively, with adhesive film 41, as seen in FIG. 8A. Adhesive film 41 is positioned between composite bridge structure 72 and first composite build up pad 36 and between composite bridge structure 72 and second composite buildup pad 38.

With composite bridging structure 72 post bonded to first and second composite buildup pads 34 and 38, respectively, the step of laying up composite bridge structure 72 further includes a step of drilling first hole 74 in a first direction 76 through first composite face sheet 22, first composite buildup pad 34, composite bridge structure 72, second composite buildup pad 38 and second composite face sheet 24. The step of laying up the composite bridge structure 72 further includes a step of drilling first portion 78 of second hole 80 in composite bridge structure 72 in a direction 82 transverse to first direction 76 placing first portion 78 in communication with first hole 74 and continue drilling second portion 84 of second hole 80 spaced apart across first hole 74 from first portion 78 of second hole 80 and aligned with first portion 78 of second hole 80. With first hole 74 and second hole 80 drilled, the step of laying up composite bridge structure 72 further includes a step of inserting barrel nut 86 into first hole 74 and inserting bolt 94 into second hole 80 and securing bolt 94 to barrel nut 86. With securement of bolt 94, first section 18 and second section 20 of wall assembly 12 are secured together as seen in FIG. 7.

A second example of a method for assembling a composite wall assembly 12 edge joint 16 includes method 200, as set forth in FIG. 10. The components of the assembly of composite wall assembly 12 edge joint 16 fabricated under method 200 that are common to previously described components for the assembling of composite wall assembly 12 edge joint 16 fabricated under method 100 are similarly numbered. As will be appreciated herein, the assembly fabricated under the second example of a method or method 200, in contrast to the assembly fabricated under method 100, the components of composite wall assembly 12 edge joint 16 under method 200 are co-cured.

In referring to FIG. 10, method 200 for assembling a composite wall assembly 12 edge joint 16, includes step 202 of laying up first composite face sheet 22, as seen in FIG. 11. In this example, first composite face sheet 22 is an inboard face sheet of this assembly. Method 200 further includes step 204 of laying up a first composite buildup pad 34 having a first tapered section 36 onto first composite face sheet 22. Step 206 includes positioning composite flute core member 26 which includes tapered first portion 42 with first inclined surface 52 and second inclined surface 64. First inclined surface 58 of composite flute core member 26 is positioned onto first tapered section 36 of first composite buildup pad 34. Second portion 44 of composite flute core member 26 extends from tapered first portion 42 along first composite face sheet 22.

Method 200 further includes step 208 of laying up second composite buildup pad 38 having second tapered section 40. Second composite buildup pad 38 is positioned spaced apart from first composite buildup pad 34 having at least a portion of second tapered section 40 of second composite buildup pad 38 overlying second inclined surface 62 of tapered first portion 42 of composite flute core member 26.

Step 204 of laying up first buildup pad 34 further includes the step of laying up of first buildup pad 34 to extend in a direction away from first end 50 of first composite face sheet 22 with first tapered section 36 having first inclined surface 52 with first tapered section having a thickness T reducing in dimension as first composite buildup pad 34 extends in direction 48 away from first end 50.

Step 206 of positioning of composite flute core member 26 further includes positioning first inclined surface 58 of composite flute core member 26 overlying first tapered section 36 having a first inclined surface 52 of first composite buildup pad 34, such that first inclined surface 58 of composite flute core member 26 increases in distance away from first composite face sheet 22 as composite flute core member 26 extends in direction 60 toward first end 50 of first composite sheet face 22.

Step 208 of laying up second composite buildup pad 38 having second tapered section 40 including configuring second tapered section 40 having a second inclined surface 64 with second tapered section reducing in thickness T′ as second composite buildup pad 38 extends in a direction 54 away from first end 50 of first composite face sheet 22. Second inclined surface 62 of tapered first portion 42 of composite flute core member 26 is positioned closer to first composite face sheet 22 as second inclined surface 62 of composite flute core member 26 extends in direction 66 toward first end 50 of first composite face sheet 22.

Method 200 further includes a step of laying up second composite face sheet 24 onto second composite buildup pad 38 and onto second portion 44 of composite flute core member 26. Second portion 44 of composite flute core member 26 extends from tapered first portion 42 of composite flute core member 26.

In fabricating composite joint edge assembly 16 under method 200, the composite material will be supported during the assembling of the composite material and co-curing of joint edge assembly 16. The supporting of the composite material will maintain the composite material in alignment and free from distortion that would otherwise be imparted to the composite material by the weight of the composite material prior to the composite material being cured. Support will be provided within interior 61 of composite flute core member 26 and within spacing 73 between first composite build up pad 34 and second composite build up pad 38, seen for example in FIG. 13.

In supporting composite flute core member 26, support is provided within interior 61 on opposing surfaces 63 of tapered first portion 42, opposing surfaces 65 of second portion 44 of composite flute core member 26 as well as opposing surfaces 79 on opposing side walls, as seen in FIG. 12. One example of supporting composite flute core member 26 includes a step of inserting pressurized gas into interior 61 of composite flute core member 26. Interior 61 is sealed off, not shown, and an access can be provided to interior 61 to adjust the pressurization within interior 61 as needed. The pressurized gas can be released from interior 61 of composite flute core member 26 when the co-curing process is completed. The pressurized gas can, as in this example, leave interior 61 of composite flute core member 26 and pass through space 73, as seen in FIG. 13, between first composite build up pad 34 and second composite build up pad 38.

Another example of supporting of composite flute core member 26 includes a step of inserting a collapsible support structure 67, as schematically shown in FIG. 12, into interior 61 of composite flute core member 26. Collapsible support structure 26 can be inserted in a collapsed position through space 73 positioned between first composite build up pad 34 and second composite build up pad 38 and through opening 69 of tapered first portion 42 of composite flute core member 26. With collapsible support structure 67 positioned within interior 61 of composite flute core member 26, collapsible support assembly 67 can be deployed such that plates 75 are positioned and provide support against interior 61 surface 65 positioned on opposing sides of composite flute core member 26 in second portion 44 of composite flute core member 26 as seen in FIGS. 11 and 12. Collapsible support assembly 67, in second portion 44 of composite flute core member 26 also includes plates 77 positioned in supporting position against interior 61 surface 79 positioned on opposing sides of composite flute core member 26 as seen in FIG. 12. Other plates of collapsible support assembly 67 (not shown) are positioned against interior surface 63 on opposing sides of tapered first portion 42 of composite flute core member 26 to provide support to tapered first portion 42 during assembly and co-curing. At the completion of co-curing collapsible support assembly 67 is collapsed and reduced in profile. Collapsible support assembly 67 is removed or otherwise pulled from interior 61 of composite flute core member 26 through opening 69 of composite flute core member 26 and then out of edge joint 16 through space 73 between first composite build up pad 34 and second composite build up pad 38. Removal of collapsible support assembly 67 through space 73 is accomplished with any obstructions in space 73 removed as needed. This is also the case with the removal of collapsible support from within tapered first portion 42 of composite flute core member 26 as needed.

Similarly support is needed to be positioned between first composite build up pad 34 and second composite build up pad 38 during assembling of edge joint 16 and during co-curing of edge joint 16. In referring to FIG. 13 a second support assembly 71 is positioned between first composite build up pad 34 and second composite build up pad 38. Second support assembly 71 is collapsible and can be inserted into space 73 in a collapsed or reduced profile and then extended and positioned against first composite build up pad 34 and second composite build up pad 38. At the time of completion of co-curing second support assembly 71, in this example, can be collapsed or reduced in profile and pulled out of space 73 and from edge joint 16.

The supporting, as discussed above, of the composite material in assembly of edge joint 16, permits the fabricator to maintain the composite material in alignment and undistorted during the assembly and through the desired co-curing process. With the support being provided by a collapsible structure or by a gas which can be released, the support can be removed from the interior of edge joint 16. In this example, space 73 that is provided between first composite build up pad 34 and second composite build up pad 38 with second support assembly 71 removed, space 73 provides the fabricator the opportunity to secure bridge composite structure 72, as will be discussed, between first composite build up pad 34 and second composite build up pad 38. With bridge composite structure 72 secured and positioned along edge joint 16, the fabricator can space bolts, as described herein, along bridge composite structure 72 as desired. The spacing of bolts along edge joint assembly 16 can provide enhanced load carrying capability with closer spacing of bolts, for example, with bolts connecting first section 18 and second section 20 of wall assembly 12. This enhanced load carrying capability is further supported with the transference of the load to the first and second buildup pads 34, 38, to the composite flute core members 26 and to first and second composite face sheets 22, 24.

Method 200 further includes a step of heating and co-curing first composite face sheet 22, first composite buildup pad 34, composite flute core member 26; second composite buildup pad 38 and second composite face sheet 24. In this example, where a circular construction of a rocket is being assembled, sections of edge joint 16 are assembled in sections up to approximately twenty degrees of the circumference of the rocket structure.

With the co-curing accomplished for edge joint 16, method 200 further includes a step of laying up composite bridge structure 72 and post bonding composite bridge structure 72 to first and second composite buildup pads 34, 38, as can be post bonded in position between first and second composite build up pads 34, 38, as seen in FIG. 11.

Method 200 further includes a step of drilling first hole 74 which extends in first direction 76 through first composite face sheet 22, first composite buildup pad 34, composite bridge structure 72, second composite buildup pad 38 and through second composite face sheet 24. Further included is a step of drilling first portion 78 of second hole 80 in composite bridge structure 72 in second direction 82 transverse to first direction 76 placing first portion 76 in communication with first hole 74. Drilling further includes drilling second portion 84 of second hole 80 positioned spaced apart from first portion 76 of second hole 80 across the first hole 74 and aligned with first portion 78 of second hole 80.

With first hole 74 and second hole 80 completed method 200 further includes a step of inserting barrel nut 86 into first hole 74 and inserting bolt 94 into second hole 80 and securing bolt 94 to barrel nut 86.

A third example of a method for assembling a composite wall assembly 12 edge joint 16 includes method 300, as set forth in FIG. 14. The components of the assembly of composite wall assembly 12 edge joint 16 fabricated under method 300 that are common to previously described components for the assembling of composite wall assembly 12 edge joint 16 fabricated under methods 100 and 200 are similarly numbered. As will be appreciated herein, the assembly fabricated under the third example of a method or method 300, in contrast to the assembly fabricated under method 200, the elements of composite wall assembly 12 edge joint 16 under method 300 employ a cured composite flute core member 26 in assembling edge joint 16.

In referring to FIG. 14, method 300 for assembling composite wall assembly 12 edge joint 16, includes step 302 of laying up composite first face sheet 22, as seen in FIG. 15. In this example, composite first face sheet 22 is an inboard face sheet of this assembly. Method 300 further includes step 304 of laying up a first composite buildup pad 34 having a first tapered section 36 onto composite first face sheet 22. Step 306 includes positioning cured composite flute core member 26 which includes tapered first portion 42 with first inclined surface 52 and second inclined surface 64. First inclined surface 52 of cured composite flute core member 26 is positioned onto first tapered section 36 with adhesive film 45 positioned between first inclined surface 52 and first tapered section 36. Second portion 44 of composite flute core member 26 extends from tapered first portion 42 along first composite face sheet 22 wherein adhesive film 45 is positioned between second portion 44 of composite flute core member 26 and composite first face sheet 22. Method 300 further includes step 308 laying up second composite buildup pad 38 having second tapered section 40 wherein second composite buildup pad 38 is positioned spaced apart from first composite buildup pad 34 having at least a portion of second tapered section 40 overlying second inclined surface 64 of tapered first portion 42 of composite flute core member 26 with adhesive layer 39 positioned between second tapered section 40 and second inclined surface 64 of tapered first portion 42 of composite flute core member 26.

Method 300 further includes a step of positioning support structure 71 between spaced apart first composite buildup pad 34 and second composite buildup pad 38, as seen in FIG. 13. Method 300 further includes a step of laying up a second composite face sheet 24 onto second composite build up pad 38 and in overlying relationship with second portion 44 of cured composite flute core member 26 with adhesive film 39, as seen in FIG. 15, positioned between second composite face sheet 24 and second portion 44 of composite flute core member 26.

Method 300 further includes a step of heating first composite face sheet 22, first composite buildup pad 34, composite flute core member 26, second composite buildup pad 38 and second composite face sheet 24. Method 300 further includes a step of laying up composite bridge structure 72 and post bonding composite bridge structure 72 to first and second composite buildup pads 34, 38.

Method 300 further includes, in this example, drilling first hole 74 in first direction 76, as seen for example in FIG. 11, through composite first face sheet 22, first composite buildup pad 34, composite bridge structure 72, second composite buildup pad 38 and second composite face sheet 24, as seen in FIG. 15. Further included is drilling first portion 78, as seen for example in FIG. 11, of second hole 80 in composite bridge structure 72 in second direction 82 transverse to first direction 76 placing first portion 78 in communication with first hole 74 and drilling second portion 84 of second hole 80 positioned spaced apart from first portion 78 of second hole 80 across first hole 74 and aligned with first portion 78 of second hole 80. Method 300 further includes inserting barrel nut 86 into first hole 74 and inserting bolt 94 into second hole 80 and securing bolt 94 to barrel nut 86.

While various embodiments have been described above, this disclosure is not intended to be limited thereto. Variations can be made to the disclosed embodiments that are still within the scope of the appended claims. 

What is claimed:
 1. A method for assembling a composite wall assembly edge joint, comprising steps of: laying up a first composite face sheet; laying up a first composite buildup pad having a first tapered section onto the first composite face sheet; positioning a composite flute core member, comprising a tapered first portion comprising a first inclined surface and a second inclined surface wherein: the first inclined surface of the composite flute core member is positioned onto the first tapered section of the first composite buildup pad; and a second portion of the composite flute core member extends from the tapered first portion along first composite face sheet; and laying up a second composite buildup pad having a second tapered section wherein the second composite buildup pad is positioned spaced apart from the first composite buildup pad having at least a portion of the second tapered section of the second composite buildup pad overlying the second inclined surface of the tapered first portion of the composite flute core member.
 2. The method for assembling of claim 1, wherein the step of laying up the first buildup pad further including the step of laying up of the first buildup pad to extend in a direction away from a first end of the first composite face sheet with the first tapered section having a thickness reducing in dimension as the first composite buildup pad extends in a direction away from the first end.
 3. The method for assembling for claim 2, wherein the step of positioning of the composite flute core member further including positioning the first inclined surface of the composite flute core member overlying the first tapered section of the first composite buildup pad such that the first inclined surface of the composite flute core member increases in distance away from the first composite face sheet as the composite flute core member extends in a direction toward the first end of the first composite sheet face.
 4. The method for assembling of claim 3, wherein the step of laying up the second composite buildup pad having the second tapered section including configuring the second tapered section with the second tapered section reducing in thickness as the second composite buildup pad extends in a direction away from the first end of the first composite face sheet with the second inclined surface of the tapered first portion of the composite flute core member positioned closer to the first composite face sheet as the second inclined surface of the composite flute core member extends in a direction toward the first end of the first composite face sheet.
 5. The method for assembling of claim 1, further including a step of supporting an interior surface of the tapered first portion and the second portion of the composite flute core member.
 6. The method for assembling of claim 5, wherein the step of supporting including a step of inserting a pressurized gas into an interior of the composite flute core member.
 7. The method for assembling of claim 5, wherein the step of supporting including a step of inserting a collapsible support structure into the interior of the composite flute core member supporting the interior surface of the first portion and the second portion of the flute core member.
 8. The method for assembling of claim 1, further including a step of positioning a support structure within space between the first composite buildup pad and the second composite buildup pad.
 9. The method for assembling of claim 1, further including a step of laying up a second composite face sheet onto the second composite buildup pad and onto the second portion of the composite flute core member which extends from the tapered first portion of the composite flute core member.
 10. The method for assembling of claim 9, further including a step of heating the first composite face sheet, first composite buildup pad, the composite flute core member; and the second composite buildup pad and the second composite face sheet.
 11. The method for assembling of claim 10, further including a step of laying up a composite bridge structure and post bonding the composite bridge structure to the first and second composite buildup pads.
 12. The method for assembling of claim 11, further including a step of drilling a first hole in a first direction through the first composite face sheet, the first composite buildup pad, the composite bridge structure, the second composite buildup pad and the second composite face sheet.
 13. The method for assembling of claim 12, further including a step of drilling a first portion of a second hole in the composite bridge structure in a second direction transverse to the first direction placing the first portion in communication with the first hole and drilling a second portion of the second hole positioned spaced apart from the first portion of the second hole across the first hole and aligned with the first portion of the second hole.
 14. The method for assembling of claim 13, further including a step of inserting a barrel nut into the first hole and inserting a bolt into the second hole and securing the bolt to the barrel nut.
 15. A method for assembling a composite wall assembly edge joint, comprising steps of: laying up a composite first face sheet; laying up a composite first buildup pad having a first tapered section onto the composite first face sheet; positioning a cured composite flute core member, comprising a tapered first portion comprising a first inclined surface and a second inclined surface, wherein the first inclined surface of the cured composite flute core member is positioned onto the first tapered section of the for composite buildup pad with an adhesive film positioned between the first inclined surface and first tapered section; and a second portion of the composite flute core member extends from the tapered first portion along first composite face sheet wherein an adhesive film is positioned between the second portion of the composite flute core member and the first composite face sheet; and laying up a second composite buildup pad having a second tapered section wherein the second composite buildup pad is positioned spaced apart from the first composite buildup pad having at least a portion of the second tapered section overlying the second inclined surface of the tapered first portion of the composite flute core member with an adhesive layer positioned between the second tapered section and the second inclined surface of the tapered first portion of the composite flute core member.
 16. The method for assembling of claim 15, further including a step of positioning a support structure between the spaced apart first composite buildup pad and the second composite buildup pad.
 17. The method for assembling of claim 15, further including a step of laying up a second composite face sheet onto the second composite build up pad and in overlying relationship with the second portion of the cured composite flute core member with an adhesive film positioned between the second composite face sheet and the second portion of the composite flute core member.
 18. The method for assembling of claim 17, further including a step of heating the first composite face sheet, the first composite buildup pad, the composite flute core member, the second composite buildup pad and the second composite face sheet.
 19. The method for assembling of claim 18, further including a step of laying up a composite bridge structure and post bonding the composite bridge structure to the first and second composite buildup pads.
 20. The method for assembling of claim 19, further including steps of: drilling a first hole in a first direction through the first composite face sheet, the first composite buildup pad, the composite bridge structure, the second composite buildup pad and the second composite face sheet; drilling a first portion of a second hole in the composite bridge structure in a second direction transverse to the first direction placing the first portion in communication with the first hole and drilling a second portion of the second hole positioned spaced apart from the first portion of the second hole across the first hole and aligned with the first portion of the second hole; and inserting a barrel nut into the first hole and inserting a bolt into the second hole and securing the bolt to the barrel nut. 